1. Field of the Invention
The present invention relates to a valve disc assembly, or valve body, for a dry barrel fire hydrant, and more specifically, to an improved valve body retention arrangement, particularly useful during field repair of the hydrant.
2. Description of the Prior Art
Improvements to water valves generally and more specifically to those for fire hydrants has inspired numerous prior art patents. Two major developments over the years have included resilient valve faces, as provided by employing rubber, and drain holes which are obstructed and revealed by the valve member. The latter feature is an improvement to the dry barrel hydrant, which was developed to combat freeze damage to hydrants in northern climes. Little has been done, however, to facilitate the repair of the hydrant valve assembly in the field.
The following references are exemplary of the art. U.S. Pat. Nos. 4,073,307, issued to John H. Royce on Feb. 14, 1978; 4,303,223, issued to Fred S. Whisenhunt on Dec. 1, 1981; 4,790,341, issued to David F. Laurel on Dec. 13, 1981; and 4,842,246, issued to Carl E. Floren et al. on Jun. 27, 1989, each disclose a valve for a fire hydrant having a rubber valve face and also having ears which, when the valve is open for operation, block drain holes. Whisenhunt '223 is also illustrative of those designs providing walls surrounding the ears formed with a valve body, the walls constraining the valve body to move only axially when the stem is rotated, and against rotation responsive to this rotation. In each of these cases, the rubber valve seat is formed on a rubber disc sandwiched between upper and lower metal retaining members. Furthermore, no structure is provided for preventing unintended disassembly of valve parts during maintenance repair work in the field.
U.S. Pat. No. 1,352,735, issued to Henry C. Egerton on Sep. 14, 1920, discloses a valve having a metal disc entirely encased in a material such as rubber. Encasement in rubber protects metal parts from deterioration from contact with water.
U.S. Pat. No. 4,227,544, issued to Lawrence F. Luckenbill on Oct. 14, 1980, discusses head losses during high flow as a consequence of the configuration of the water passageway. The valve body is provided with frustoconical portions to assist in reducing turbulence and head pressure losses. U.S. standards for fire hydrants now include limits on head losses.
Rubber encasement of the valve body is seen, in combination with a valve body designed to be streamlined for reduced resistance to liquid flow, in U.S. Pat. No. 3,310,277, issued to Helmar T. Nielsen et al. on Mar. 21, 1967, and European Patent Office Application No. 0,092,482, dated Oct. 26, 1983.
The devices of Egerton '735, Nielsen et al. '227, and EPO reference '482 are not directed to hydrant valves, and the respective valve bodies, when opening, move in the same direction as water flow, and are not hollow. This is in contrast to the practice of hydrant valves, wherein, at least in most recent designs, the valve opens against the direction of water flow.
A still more streamlined valve body is shown in U.S. Pat. No. 2,980,125, issued to Allen F. Grant et al. on Apr. 18, 1961. The streamlined body is made in mating halves, the valve being hollow and accessible, so as to house cooperating ears (elements 70) and legs (elements 75). This arrangement prevents the valve body from rotating, the valve body thus being constrained to move only axially, vertically, in response to rotation of the control shaft assembly operated by rotation of upper wrench lug (element 167).
Other prior art patents of interest include U.S. Pat. No. 2,202,735, issued May 28, 1940 to John S. Johnson, which teaches the coating of a reciprocating valve with a resilient material (e.g., vulcanized rubber) and U.S. Pat. No. 2,469,109, issued May 3, 1949 to Rudilfe F. Goecke, disclosing a reciprocating valve body covered with a corrosion resistant material (e.g., glass enamel). German Patent No. 16 05 558 to E. Schnabel and dated Sep. 8, 1977 shows a valve body coated with a plastic material (e.g., polytetrafluoroethylene).
None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed.